Histogenesis of Peyer’s patches in Ovine foetus (Ovis aries)

Abstract

Tissue pieces of jejunum and ileum from different prenatal age groups of sheep were collected from Corporation slaughter house, Perambur, Chennai. By three months of foetal age in sheep, the Peyer’s patches appeared as an aggregation of lymphocytes in the propria submucosa of the jejunum and ileum. The lymphocytic aggregation appeared only in the antimesenteric part of the jejunum and ileum. By four months of foetal age, the circumscribed nodular aggregations of lymphocytes were found enlarged giving a follicle-like appearance. The capsular connective tissue was predominated by reticular fibres and a few collagen fibres. The dome area of the follicle consisted of closely packed small-sized lymphocytes which appeared darker than the basal area. The smooth muscle fibres of muscularis mucosae were not continuous throughout and were absent in the follicle having domes. In five months-old foetuses, the jejunal and ileal Peyer’s patches were distinctly observed as follicles. The follicle showed a distinct outer cortex and an inner lighter medulla. Numerous small-sized lymphocytes were observed in the outer cortex and few lymphoblasts, medium sized lymphocytes and reticular cells were observed in the medulla.